Generally, under the 1990 Appellate Division case of Winer v. Winer, “[a]n engagement ring is a conditional gift. The condition [of the gift] is marriage and the ring is returnable only if the engagement is broken.” Further, under the 1987 Chancery Division case of Aronow v. Silver, “[i]t does not matter who broke the engagement. A person may have the best reasons in the world for so doing. The important thing is that the gift was conditional and the condition was not fulfilled.”
Nevertheless, in unusual circumstances, the recipient of the engagement ring may be able to establish that it was in truth an unconditional gift. If the ring was really a normal gift, rather than an engagement ring, there is no need to return it.
In the 2013 case of Sipko v. Koger, Inc., the New Jersey Supreme Court held that the recipient of the gift must prove four elements by “clear, cogent and persuasive evidence” to establish that a gift was unconditional: “First, the donor must perform some act constituting the actual or symbolic delivery of the subject matter of the gift. Second, the donor must possess the intent to give. Third, the donee must accept the gift. Our cases also recognize an additional element, the relinquishment by the donor ‘of ownership and dominion over the subject matter of the gift.’” Our Supreme Court went on to state, if the gift is “absolute and made voluntarily with a full understanding of its effect[, it] cannot be revoked by the donor, either by his act alone or with the aid of a judicial tribunal.”
So, in all but the most unusual circumstances, you will be required to return the ring if the matter is brought to Court.